Also, if it's just a firmware issue, can't that be resolved by a simple download and update?
Even for a firmware it's certainly possible that Canon would reschedule shipments in order to ship updated cameras. I mean it's not like this would be the first time that a dealer was wrong about why a manufacturer did something, there's been countless times where dealers have claimed something was discontinued when it wasn't, simply because they couldn't get any stock.
Maybe, but 800/5.6 and 200/2 owners are few so I doubt a camera wide re-call. I'll send in my 5D3 for my 200/2 if I had too. Free shipping all around of course, and not cheap mail, I'm talking overnight FedEx/UPS.
Even then, if fixing it required more than just a firmware it would warrant at least a service notice for cameras in the wild and possibly holding up shipments of unshipped cameras. While the numbers of 200/2 and 800/5.6 users are small, Canon can't assume that any given 5D III (especially unshipped ones) won't be going to 200/2 or 800/5.6 users. On the other hand, while the need to return the camera might be minimal (and certainly not immediate) if you aren't a 200/2 or 800/5.6 user, and it wouldn't warrant not being called a "recal" if cameras have to be shipped back.
Then again, it wouldn't be the first time a dealer was wrong/inaccurate for one reason or another. Never mind it's not that far for someone to leap between being told their shipment was being held and finding out that there may be a service notice issue, to leaping to the conclusion that there's going to be a product recall. Never mind by the time we read it here, you're talking about something that's likely gone from someone in Canon JP making a decision, through Canon USA, though a distributor, to the purchasing agent for a camera store, to Canon Rumors, likely not verbatim either.
maybe they found the problem for the AF not working at F8?
As nice as that would be, I'm not convinced that this is a rectifiable issue without replacing rebuilding the optics in the AF path and potentially the AF sensor itself. It's been a while since I looked at it, but the reduced aperture at f/8 reduces the effective base length for the range finder, and would require either a stronger shift between the phases or a more finely grained AF sensor strip, to be able to insure accurate focus.